The present invention relates generally to packet telephony systems, and more particularly, to methods and apparatus for minimizing the bandwidth utilization in such packet telephony systems.
Communication networks are used to transfer information, such as data, voice, text or video information, among communication devices, such as packet telephones, computer terminals, multimedia workstations, and videophones, connected to the networks. A network typically comprises nodes connected to each other, and to communication devices, by various links. Each link is characterized by a bandwidth or link capacity.
Within a corporate environment, telephone service has typically been provided by a private branch exchange (PBX) switch. Generally, a private branch exchange switch is an on-site facility, that is typically owned or leased by a company or another entity. The private branch exchange interconnects the telephones within the facility and provides access to the Public Switched Telephone Network (PSTN). The centralized PBX controls all aspects of a telephone connection. For example, if a given calling party is placed on hold, the PBX may respond by transmitting a music source to the calling party for a music-on-hold feature. In any event, the bandwidth that is allocated to a given call (typically 64-Kbps in each direction) is maintained for the entire length of the call, even during periods of extended silence, such as when a call is placed on hold, or when one caller utilizes a mute feature.
Information sent from a communication device to a network may be of any form, but is often formatted into fixed-length packets or cells. Packet-switching network architectures are widely used, for example, in popular local-area network (LAN) protocols, such as Ethernet and asynchronous transfer mode (ATM) protocols. In a packet-switched network, data transmissions are typically divided into blocks of data, called packets, for transmission through the network. For a packet to get to its proper destination, the packet must traverse through one or more network switches, routers or intermediate systems. Typically, a packet includes a header, containing source and destination address information, as well as a payload (the actual application data). Increasingly, such packet telephony systems are being utilized in corporate environments. Unlike a PBX environment, the packet data network used by the packet telephony system is typically shared with other network applications, such as web browsers, electronic mail, file and print servers. To avoid disrupting and degrading other applications that operate on the shared network, it is important to minimize network usage when possible.
A need therefore exists for a mechanism for suppressing the transmission of packets during periods of extended silence, for example, when a call is placed on hold, or when one calling party utilizes the traditional telephony xe2x80x9caudio mutexe2x80x9d feature. A further need exists for a method and apparatus that generates music for a music-on-hold feature locally at the terminal of the party that is placed on hold. Yet another need exists for a method and apparatus that automatically suppresses the transmission of packets that will not be processed by the receiver, such as an automated interactive voice response unit (IVR) or a voice mail system before recording commences. Another need exists for a method and apparatus that notifies a calling party when another calling party utilizes a hold or mute feature.
Generally, a method and apparatus are disclosed for notifying a far-end calling endpoint when a near-end calling party utilizes a hold or mute feature. The present invention reduces bandwidth utilization by suppressing the transmission of packets during periods of extended silence. Periods of silence are experienced, for example, when a call is placed on hold, or when packets will otherwise not be processed by the receiver, such as an automated interactive voice response unit or a voice mail system before recording commences. If a near-end party activates the xe2x80x9choldxe2x80x9d feature, then the near-end party is both ignoring anything sent by the far-end device and is not sending any meaningful media to the far-end device.
According to one aspect of the invention, each device in a packet telephony system includes a packet suppression system that monitors local user or application activity (such as activating the xe2x80x9choldxe2x80x9d feature) and notifies the far-end party that the near-end device is discarding the xe2x80x9clistenxe2x80x9d stream. In addition, the packet suppression system of the present invention monitors the incoming packets and processes such notifications from the far-end party that the far-end device is discarding the xe2x80x9clistenxe2x80x9d stream. In response, the packet suppression system can suppress the transmission of further packets and optionally activate a music-on-hold feature for the held party. In this manner, the bandwidth consumption and resource utilization at both the near and far-end devices are minimized by suppressing the transmission of further packets until the far-end device indicates that it is again utilizing the xe2x80x9clistenxe2x80x9d stream. The near-end device can implement a music-on-hold feature, for example, by switching the input stream for the speaker/handset from the silent xe2x80x9clistenxe2x80x9d stream to an appropriate audio source.
A more complete understanding of the present invention, as well as further features and advantages of the present invention, will be obtained by reference to the following detailed description and drawings.